As flat panel displays featuring thinness, light weight, etc., liquid crystal display devices have recently been used widely for liquid crystal television devices, monitor devices, mobile phones, and the like. However, the liquid crystal display devices which are now used most widely are of a type that uses one or two polarizers, which invites the problem of low efficiency of light utilization.
As displaying methods which do not use polarizers, a method utilizing a guest-host liquid crystal and a method utilizing a polymer dispersed liquid crystal have been proposed in the past. However, because of disadvantages such as a low contrast ratio and a high driving voltage, these methods are yet to be put to practical use.
Furthermore, as another displaying method which does not use polarizers, a method of controlling total reflection/transmission at an interface between a liquid crystal layer and a substrate or a light guiding plate (hereinafter referred to as “total-reflection type”) has been proposed.
For example, Patent Document 1 discloses a display device which, by varying the orientation state of a liquid crystal layer, switches between a state where light propagating through a light guiding plate which is disposed adjacent to the liquid crystal layer is totally reflected at an interface between the liquid crystal layer and the light guiding plate or a state where it is transmitted, thus conducting black displaying in the total reflection state or conducting white displaying in the transmitting state. White displaying is realized by allowing the light which is emitted from the light guiding plate to be scattered by a scattering plate. A liquid crystal display device disclosed in Patent Document 2 includes a light guide, a liquid crystal layer, and a reflective film in this order, and by varying the orientation state of the liquid crystal layer, switches between a state where light entering the liquid crystal layer from the light guide is totally reflected at an interface between the liquid crystal layer and the light guide or a state where it is transmitted, and conducts white displaying by reflecting light which has been transmitted through the interface toward a viewer with a reflective film. Furthermore, Patent Document 3 discloses a display device which, by using as a light guiding plate a transparent substrate containing a fluorophore, conducts displaying by switching between a state of totally reflecting fluorescence which is emitted from the light guiding plate or a state where it is transmitted, in a manner similar to Patent Document 1.    [Patent Document 1] Japanese Laid-Open Patent Publication No. 59-58421    [Patent Document 2] Japanese Laid-Open Patent Publication No. 2000-171813    [Patent Document 3] Japanese Laid-Open Patent Publication No. 63-116121